/**
 * @author 善诚
 * @desc 星星
 * 模块化， 多人协作
 */

function RoundItem(index, x, y, ctx) {
    this.index = index
    this.x = x
    this.y = y
    this.ctx = ctx
    this.r = Math.random() *2　+ 1
    this.color = 'rgba(255, 255, 255, 1)'
}

RoundItem.prototype.draw = function () {
    this.ctx.fillStyle = this.color
    this.ctx.beginPath()
    this.ctx.arc(this.x,this.y,this.r,0,2 * Math.PI,false)
    this.ctx.closePath()
    this.ctx.fill()
}

RoundItem.prototype.move = function() {
    this.y -=0.3
    this.draw()
}